Mercury switch structure



1954 R. BROWN ET AL MERCURY SWITCH STRUCTURE Filed March 31, 1952 RALPH Bean 1v, RICH/72D A. MLLAOEJ'Q- INVENTORS.

ATTQQNEY.

UnitedStates Patent MERCURY SWITCH STRUCTURE Ralph Brown, Fallbrook, and Richard A. Wallace, Jr., Tujunga, Calif., assignors to General Controls Co., Glendale, Calif., a corporation of California Application March 31, 1952, Serial No. 279,636

6 Claims. (Cl. 200152) This invention relates to mercury switches of the tiltable type.

It is common to provide a sealed cylindrical glass container having recesses for the accommodation of pools of mercury. Electrodes are supported by the body and respectively extend into the pools. When it is desired to close the switch, the container is tilted and the mercury pools merge together. A tilt in the opposlte direction will cause the pools to break and open the switch.

Switches of this character are especially adapted for operation in response to temperature changes as, for example, by flexing of a bimetal strip. The temperature differential between open and closed position is determined by the angle of tilt through which the container moves for making and breaking the contact between the pools. Accordingly, the smaller this angle, the narrower is the range of temperature necessary to operate the switch. 7

It is one of the objects of this invention to make it possible to reduce this angle, especially by a particular configuration of the mercury recesses or wells. By utilization of this invention, the further advantage is obtained that the container can be made shorter.

The amount of force required to tilt the container is appreciable, since the mercury in it has substantial weight. This force should be kept at a mmimum to maintain the accuracy of the control (whether of temperature or of any other condition).

It is another object of this invention to provide a switch of this character in which the force required to tilt the container may be substantially reduced.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of one embodiment of the invention. For this purpose, there is shown a form in the drawings accompanying and forming part of the present specification. The form will now be described 1n detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best defined by the appended claims.

Referring to the drawings:

Figure l is a side elevation of a mercury switch embodying the invention, and shown as mounted upon a bimetallic element, the mercury switch being in closed position;

Fig. 2 is a vertical sectional view of the mercury switch in closed position;

Fig. 3 is a view similar to Fig. 2, but illustrating the switch in open position;

Fig. 4 is a sectional view, taken along a plane corresponding to line 4-4 of Fig. 2;

Fig. 5 is a cross-sectional view, taken along a plane corresponding to line 5-5 of Fig. 3; and

Fig. 6 is a pictorial view of the mercury switch.

The mercury switch includes a sealed container 1 made of glass, or other insulation material. The container is preferably filled at low pressure with a gaseous element, such as hydrogen. This container is of general cylindrical configuration. Electrodes 3 and 4 extend through an end wall of the container 1, and serve, as hereinafter described, to form connections to mercury pools. The switch may be included in a circuit by appropriate connections to the exposed ends of the electrodes 3 and 4.

Container 1 is adapted to be tilted for operating the Switch. In the present instance, this tilting is effected by the flexure of a bimetallic element 5 anchored at one end, as on a bracket 6. Its free end carries a pair of clips 7 which resiliently embrace the body 1. Obviously, other mountings could be substituted for that illustrated.

A pair of recesses to form the mercury pools is provided in the lower portion of the container 1. One of these recesses 8 is in the form of a generally circular depression adjacent the left-hand end of the container. The electrode 4 has a downwardly turned end 9 adapted to extend into this recess. In the open position of Fig. 3, a pool 10 of mercury is formed around this end 9.

Another recess 12 is formed into which the downwardly turned end 11 of electrode 2 extends. This recess is so shaped that it causes separation of the mercury into the two pools 8 and 13 (Fig. 3) upon a relatively slight angular movement of the container 1 from the position of Fig. 2 to the position of Fig. 3. This separation is indicated, in the present instance, as correspond-v ing to about two and one-half degrees of angular movement. In other words, one and one-quarter degrees of upward or downward movement from a central horizontal position will cause either opening or closing of the switch. These angular values are merely examples and, in some instances, the angular movement may be even less.

In order to cause this separation of the mercury into isolated pools 10 and 13 even upon a slight angular movement, the recess 12 is formed in a specific manner. Thus, it has vertical side walls having substantially parallel portions 14 and 15 (Figs. 4, 5, and 6). These parallel portions extend downwardly below the main portion of the container 1. Joined to walls 14 and 15 are walls 17 and 18 that diverge away from the other recess 8 and toward the righthand end of container 1. The bottom wall 19 has a portion 20 which slopes upwardly toward the right-hand end of the container 1, remote from that end near which the recess 8 is formed.

Due to the provision of the sloping bottom wall 20 and of the outwardly diverging walls 17 and 18, separation of the mercury into two pools is rendered possible for relatively small angular movement of the container 1.

Thus, in Fig. 2, the container 1 is tilted so that the body of mercury within the container 1 is in electrical contact with both of the electrodes 3 and 4. A relatively small tilting movement in a clockwise direction separates this body of mercury into the two pools 10 and 13. During this tilting movement the pool 13 spreads laterally into the space defined by the diverging walls 17 and 18.

The left-hand end of the recess 12 is deep enough, as a retainer for pool 13, to make electrical contact with the end 11 even when the container 1 is tilted to the position of Fig. 3. The sloping bottom wall 20 causes closing of the switch, upon counterclockwise tilting, by flow of the mercury pool 13 toward the mercury pool 10.

The provision of the well or recess 12 in which the mercury body can spread sidewise, upon angular movement, also makes it possible to utilize a relatively short container 1. Furthermore, the extent of movement of the relatively heavy mercury between the open and closed position is slight and,'accordingly, the force required to tilt the container 1 between the two positions is quite small.

The inventors claim:

1. In a mercury switch: a container having a lower interior surface formed to provide an elongate channel, said container having a wall extending transversely of the channel near one end thereof to divide said channel into a pair of longitudinally spaced recesses, one of the recesses being of a greater length than the other recess, said recesses being in communication over said wall; said one recess having an increasing transverse width in a direction away from the other recess; and mercury in said container and adapted to form pools in the recesses.

2. In a mercury switch: a container having a lower interior surface formed to provide an elongate channel, said container having a wall extending transversely of the channel near one end thereof to divide said channel into a pair of longitudinally spaced recesses, one of the recesses being of a greater length than the other recess, said recesses being in communication over said wall; said one recess having an increasing transverse width in a direction away from the other recess; the bottom of said one recess sloping upwardly in a direction away from said other recess; and mercury in said container and adapted to form pools in the recesses, the pools merging together 'up'on tilting the Container in one direction, the mercury in said one recess terminating at said sloping portion when the pools are initially separated;

3. In a mercury switch: an elongate container having a bottom interior surface concavel y curved in a trans v'erse plane, said Container having an elongate channel opening in the lowermost portion of saidcurved sn'rfae of said container, said container having a wall extending transversely of the channel hear one end thereof, the top of said Wall being substantially at the level of said container surface, said Wall defining a pair of longitudinally' spaced recesses, one of the recesses being of a greater length than the other recess, said ree'esses sang in communication with each other over said Wall and the adjacent walls of said channel; said one re'c'es's havin'g an increasing transverse width in a direction away from the other recess; and merciiry in said container and adapted to form pools in the reees'ses.

4: In a mercury switch: an elongate container having a bottom interior surface concavely curvd in a transverse plane, said container having an elongate channel opening in the lowermost portion of said curvedsurface of said container, said container having a wall extending transversely of the channel near one end thereof, the

top of said wall being substantially at the level of said container surface, said wall defining a pair of longitudinallyspaced recesses, one of the recesses being of a greater length than the other recess, said recesses being in. com munication with each other over said wall and the adja cent Walls of said channel; said one recess having a lower surface sloping upwardly in a direction away from said other'recess; and mercury in said container and adapted to form pools in the recesses. I

5. In a mercury switch: an elongate container having a bottom interior surface concavely curved in a trans verse plane, said container having an elongate channel opening in the lowermost portion of said curved surface of said container, said container having a wall extending transversely of the channel near one end thereof, the top of said wall being substantially at the level of said container surface, said wall defining a pair of longitudinally spaced recesses, one of the recesses being of a greater length than the other recess, said recesses being in communication with each other over said wall and the adja cent walls of said channel; said one recess havi'nga lower surface sloping upwardly in a direction away from said other recess; said one recess also having an increasing transverse Width ina dire'ctionaway from the other recess; mercury in said container and adapted to form pools in the recesses.

6. In a mercury switch: a container having a lower interior surfaceforrned to provide an elongate channel, said container having awall extending transversely "of the channel near one end thereof to divide said-channel into a pair of lon itndinally spaced recesses, one of the recesses being of a greater length than the other -re'c'ess, said recesses being in comm'uri'ica'ti'on over said Wall; the bottom of said one recess sloping upwardly in a direction away from said otherrecess'; and mercury in said cantainer and adapted to form pools in the recesses, the pools merging together up'on tilting the container in one direction, the mercury in said one recess terminating at said sloping portion when the pools are initially separated.

Rererenes Cited in the file of this patent- UNITED STATES i A'rENrs 

